Attached is a circuit I have been using for a few months to allow a WRT54G wireless router to remotely control a 220v pump motor for irrigation. (Not Arduino related but...)
Lately I have noticed that it will sometimes spontaneously go from "off" to an "oscillating" state, that is, the contactor turns on and off about 5-10 times per second.
Is there something I'm overlooking in my calculations or design?
I think the gpio from the router will source/sink 4ma.
The SSR is an OAC5 http://www.opto22.com/documents/0449_Std_Dig_AC_Outputs_data_sheet.pdf. It wants input 2.5-8v and 12ma.
It may be a week or two until I can actually go to the location to try and diagnose. Even then I'm not sure how to diagnose since it is intermittent. But there is a second pump installation there which uses the same circuit and is not having the problem. Of course it could be a bad component or a loose connection...